In erythrocyte membranes, solubilization and purification of calcium binding protein have not been done extensively. We were able to solubilize two different types of calcium binding proteins from human erythrocytes. We will study the physico-chemical properties as well as biochemical activities. In sickle cells, the calcium pump seems to be impaired. We will study whether there is any detectable abnormality in the quantity and/or the Ca-binding constant of this protein in sickle cells.